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1.
any pair of pants, where the wearer can feel comfortable and without worry about how they looked, only that they are the most comfortable pants ever.
fat pants may be: old, a size too large, or stretched from excessive use.
Before the movie started, all the girls prepared for girls' night by making popcorn, getting out ice cream, and putting on fat pants.
by sd489 October 16, 2005
 
2.
worn by mad shuffling ravers... usually bright, loud colours, shapes, patterns etc....almost cut like low rider flares. large and hidden pockets for your stash....
dude! did you see that guys fat pants??
they look fukin hot!!
by head bopper..... December 29, 2005
 
3.
pants which must be purchased because the wearer has gained so much weight
I have to go buy some fat pants today because I gained so much weight at the company's free luncheons, that my old ones are too small. What's that about?
by wsfc March 28, 2005
 
4.
Stretchy-elastic-waisted pants that women resort to wearing when they can't get their jeans zipped. They are often the result of holiday eating, are dark in color, and usually worn from November 30 through January 10.
"Hi Kathy, I haven't seen you wear those pants before"

"Yea, I put on a few pounds and everything else is too tight so I am wearing my fat pants"
by bingo-lingo November 30, 2009
 
5.
For a fat bitch who cant fit in real pants.
damn i can't fit in these jeans....better chuck on my fat pants
by Kripdick July 06, 2014